Conventional joints, used to connect one or more pipes, usually have the disadvantage of not being able to provide an adequate sealing force to withstand axially-oriented stresses.
In particular, in the presence of a thermal exchange with a conveyed fluid, the pipes may be affected by deformation (in the form of, for example, elongations or shortenings) along the axial direction. Conventionally, these deformations are not compensated by a joint. For example, conventional threaded or flanged joints are rigid types of connections, and do not allow the pipe to deform freely in the vicinity of the junction area. In this way, the pipe is forced not to deform, and will transmit the entire stress on the joint.
To obviate this drawback, it is known to leave the pipe partially free to slide within the joint. An example of a coupling configured in the above manner is disclosed in patent publication EP 2 202 441.
The above document describes that inside a joint a cylindrical chamber can be formed which slidably receives an annular sleeve. The sleeve is provided with mutually opposite cylindrical walls, between which one end of the pipe is locked. An annular clamp is arranged in a radially retracted position, which clamps the pipe to prevent it from slipping out of the sleeve.
However, a solution of the aforementioned type is affected by the lack of a sufficient mechanical seal between the sleeve and the pipe, despite the presence of the annular clamp. In fact, when the pipe is subjected to considerable axial deformation, the connection between the sleeve and the pipe is ensured solely by pressure forces. Consequently, if a sufficiently strong axial force is applied, neither the pressure force exerted by the interlocking sleeve, nor the containing action of the annular clamp are sufficient to prevent the pipe from being pulled out of the joint.